A state of polywater intoxication (sometimes referred to as the Psi 2000 intoxication, the Psi 2000 virus or the Tsiolkovsky infection) was an affliction caused by polywater molecules, first noted on Psi 2000. It was spread through contact with infected perspiration or blood. The main symptom of the intoxication was the suppression of inhibitions, resulting in an effect that appeared much like drunkenness.

It first affected the members of a Federation science team stationed on the planet from which it was named in 2266. The transmission of the affliction was water-based, caused by huge shifts in gravity, resulting in complex strings of water molecules that had the ability to propagate themselves, much like a very simple version of a virus. Polywater-infected blood also demonstrated the ability to melt itself from a frozen state, move along surfaces and jump for short distances to infect a host.

The disease was spread to the crew of the USS Enterprise (which was conducting a study of Psi 2000's disintegration). As a result, the ship was nearly destroyed when the affected LieutenantKevin Riley disabled the ship's engines; a disastrous move aboard a ship in orbit around a disintegrating planet. The cure was developed by Dr.McCoy. (TOS: "The Naked Time")

The Enterprise-D computer database held the formula for the cure used aboard the NCC-1701 Enterprise. However, this was not successful in treating the intoxication. Due perhaps to the higher gravity of the star, this intoxication was more severe, requiring Doctor Beverly Crusher to create a broader remedy. (TNG: "The Naked Now")